This is book number 2 in the Future Shock series.
The second book in the New York Times best-selling Future Shock trilogy
Six months ago Aether Corporation sent Elena, Adam, and three other recruits on a trip to the future, from where they brought back secret information - but not everyone made it back to the present alive. Now Elena's dealing with her survivor's guilt and trying to make her relationship with Adam work. All she knows for sure is that she's done with time travel and Aether Corporation.
But Aether's not done with her - or Adam, or fellow survivor Chris. The travelers on Aether's latest mission to the future have gone missing, and Elena and her friends are drafted into the rescue effort. They arrive in a future that's amazingly advanced, thanks to Aether Corporation's reverse-engineered technology. The mission has deadly consequences, though, and they return to the future to try to alter the course of events.
But the future is different yet again. Now every trip through time reveals new complications and more lives lost - or never born. Elena and Adam must risk everything - including their relationship - to save their friends.